Single Beam Acoustic Data

For single beam acoustic surveys we employ a Simrad EK60  (120 Hz) scientific echo sounder. The sounder output is logged and the data is analysed in Echoview software supplied by SonarData Pty Ltd (http://www.echoview.com/).

Field transects are sampled at regular intervals (generally 50-100 m apart) in a 'zig-zag' pattern along the coastline, or more frequently where habitats change rapidly or have patchy distributions. ArcPad 6 (ESRI) is employed in the field to display previous transects to help maintain a regular field sampling regime and to display drafted habitat polygons captured from aerial photographs, which helps in targetting habitats smaller than the transect spacing.

Bathymetric output it processed for tidal corrrection to the local port and checked for errors. Benthic habitats are interpreted by integrating the tail of the first echo (roughness) and the entire second echo (hardness) and validated using both an underwater video camera and sediment grab samples. Habitats are broadly classified from single beam acoustics at Level 1 or Level 2 of the SeaMap Tasmania hierarchical classification scheme (Geomorphic type and Biogeomorphic type). 

Further details on the field methodology are available in each of the SaMap Tasmania reports.